Field of Invention
The present invention relates to steering wheels. More particularly, the present invention relates to a steering wheel equipped with a so-called self aligning mechanism through which when an impact force is exerted on the steering wheel ring, the plane of that ring realigns so as to be substantially normal to the impact force line of action.
FIGS. 10 and 11 (Prior Art) illustrate one example of a known steering wheel WO equipped with a self aligning mechanism. One such known use of this self aligning mechanism is disclosed in Japanese Unexamined Patent publication No. sho. 60-261751.
FIG. 10 (Prior Art) illustrates a spoke portion S of the steering wheel WO connecting the boss portion B and the ring portion R. The spoke portion S is depicted as including two spokes S(1) and S(3) disposed on the left and right sides of the front and a spoke S(2) disposed at the rear. Each spoke is provided with a spoke core member concealed therein.
FIG. 11 (Prior Art) illustrates a boss portion B having a boss 1 and a boss plate 2. The boss plate 2 couples with the core member in each of the respective spokes. In this known steering wheel, whenever an impact force F acts on the steering wheel ring R, the boss plate 2 plastically deforms, thus performing the so-called self alignment by which the plane P is aligned to be normal to the acting direction of the impact force.
The boss plate 2 is constructed of a plate 2a to which the spoke members 4 of the respective spokes are mechanically joined, such as through welding, and a deformable portion 2b, which extends radially to connect the plate 2a and the boss 1 together. The boss plate 2 is also provided with a plastically deformable arm 2c.
In the steering wheel WO, a generally planar core member 4 within the spoke S2 extends from the steel core 3 in the ring portion R from the horizontal plane of the ring portion P to the boss plate 2. Through this arrangement, when an impact force F is exerted on the ring portion R, the spoke core member 4 serves to smoothly transmit the impact force F to the boss plate 2 while resisting any bending movement midway between the portion connected to the ring steel core 3 and the portion connected to the boss plate 2.
As a result, the deformable portion 2b of the boss plate 2 is smoothly plastically deformed so as to realign the ring plane P to be normal to the impact force line of action. However, in the conventional steering wheel, the connected portion of the spoke portion with the ring portion R could not be parallel to the ring R. Therefore, there are many restrictions in design.